Asynchronous transfer mode adaptation layer 0 and 1 segmentation and reassembly (ATM AAL0/1 SAR) internetworking functions can require large amounts of high-speed memory for storage of timeslots and cells during the “timeslot to cell” and “cell to timeslot” conversions. For example, typical solutions may employ two buffers of 53 octets' worth of high-speed on-die memory per implemented virtual channel (VC). When implementing solutions for high channel counts, the amount of memory required for these buffers may represent a significant portion of the overall die space. This, in turn, increases the cost of ATM solutions.
One aspect of the invention disclosed in the '769 application provides a segmentation and re-assembly apparatus for interfacing with a cell delay variation buffer and a re-assembly memory buffer. Using two separate buffers allows the Cell Delay Variation (CDV) buffer to be implemented in a relatively less-expensive form of memory. In an illustrative embodiment, the apparatus can include a header and sequence number processing module that is configured to obtain a plurality of cells, and a cell delay variation buffer interface that is coupled to the header and sequence number processing module, and is configured to interface with the cell delay variation buffer. The illustrative embodiment can further include a re-assembly processing module that is coupled to the header and sequence number processing module, and a re-assembly memory buffer interface that is coupled to the re-assembly processing module and is configured to interface with the re-assembly memory buffer. The header and sequence number processing module can be configured to cause payloads from the cells to be stored in annotated form through the CDV buffer interface, and to cause a given one of the annotated payloads to be exacted through the interface. Payload information of the extracted annotated payload can then be passed to the re-assembly processing module. The re-assembly processing module can cause the payload information received from the header and sequence number processing module to be stored and retrieved through the re-assembly memory buffer interface.
Another aspect of the invention disclosed in the '769 application includes, in an exemplary method of processing cells in a communication system, the steps of obtaining a plurality of cells, causing payloads from the cells to be stored in annotated form in a CDV buffer, causing a given one of the annotated payloads to be extracted from the CDV buffer, causing payload information from the extracted annotated payload to be stored in a re-assembly memory buffer, and causing the payload information to be extracted from the re-assembly memory buffer.
Despite the fact that the invention disclosed in the '769 application represented a considerable advancement, still further improvements would be desirable.